====== Access types ======
===== Definitions =====
==== access_type_definition ====
''access [[.:bnf#subtype_indication]]''

By declaring an access type an access type is declared which can later be used for declaring an index variable.

==== incomplete_type_declaration ====
''type [[.:bnf#identifier]]''

By giving an incomplete type declaration it is possible to model recursive structures. The complete type declaration has to be made in the same declarative range.

===== Examples =====
Access types //address// and //buffer_ptr// are declared. //memory// and //buffer// are target //types// .
<code vhdl>
TYPE address IS ACCESS memory ;

TYPE buffer_ptr IS ACCESS buffer ;
</code>

----

A recursive structure is created. At first type //cell// is declared incompletely. As a consequence the access type //link// is declared on the type //cell// .

Afterwards type //cell// is declared completely as Record. The elements //succ// and //pred// are declared as index types. By doing so an interlinked list can be created in which every element receives an index to both its predecessor and its successor.
<code vhdl>
TYPE cell ;

TYPE link IS ACCESS cell ;

TYPE cell IS
   RECORD
      value : integer ;
      succ  : link ;
      pred  : link ;
   END RECORD ;
</code>